First operation of GridPix in double phase Liquid Argon Patrick Decowski Gijs Hemink Mattheo Alfonsi...

First operation of GridPixin double phase Liquid Argon

Patrick DecowskiGijs HeminkMattheo AlfonsiRolf SchonNiels van BakelMaarten van DijkHarry van der Graaf

Nikhef, Amsterdam

6th Workshop RD-51, Bari, Oct 8, 2010

4th RD51 Collaboration Meeting-

Maarten van Dijk

WIMP search, bi-phase Xenon

• GridPix TPC

as

WIMP / DBD

detector Source: Direct Searches for Dark Matter, Elena Aprile, EPS - HEP, July 21 2009, Krakow, Poland

XENON

DARWIN: European R&D project for bi-phase missing mass/energydetectors

With InGrid TPC:- detection of single, individual electrons

essential: granularity and the very small source capacitance at pixel input- high (95 %) single electron efficiency- accurate X, Y and Z (timing) precision- potentially: (UV) photon detector

With GridPix, a detector is superimposed onto the (PM/QPID) detection system

4th RD51 Collaboration Meeting-

Maarten van Dijk

Gridpix in Xenon: Test setup

• Collaboration DARWIN/XENON Columbia Univ., N.Y.

55Fe in pure argon,HVgrid = 350 VP = 1 barT = -70 Cat NLR cryostat

gain: ~ 200 !

- TimePix chip: proved to work at – 100 C- confirmed – 83 C in our work- Would TimePix work at -160 C (LAr temperature?)

- Gas gain in pure Ar, pure Xe: measured G = ~ 200. Purity?

- Special pixel chip (TPX-?) may have noise < 20 e-

- Discharge stability: influence protection layer? UV photon propagation?

- Required HV: 350 V. Steep gain/HV relation. Pure Ar proportinal wire tube: 600 V!

- Max reachable gain (@NTP) with Micromegas versus single GEM

4th RD51 Collaboration Meeting-

Maarten van Dijk

Expanding GridPix?

• Photoelectric effect• Future possibility:

CsI layer on grid